The proposed research is designed to aid in the development of dental filling materials with improved wear resistance through systematic investigation of the fundamental processes responsible for physiological wear. The objective is pursued in two complimentary ways using recently developed instrumentation designed to test for pure sliding wear and for pure normal or compound impact wear. The two novel wear-testing instruments were designed and constructed at the University of Connecticut and are unique in their capabilities, controllability and applicability to studies of wear of dental restorative materials. Using our laboratory system dental filling materials can be subjected to stress histories which replicate those experienced in vivo. This will allow for the rapid determination of the resistance of various dental filling materials to wear against carefully prepared sections of human tooth before they are subjected to time-consuming, extensive clinical evaluation.